摘要
Microglia shape the synaptic environment in health and disease,but synapses do not exist in a vacuum.Instead,pre-and postsynaptic terminals are surrounded by extracellular matrix(ECM),which together with glia comprise the four elements of the contemporary tetrapartite synapse model.While research in this area is still just beginning,accumulating evidence points toward a novel role for microglia in regulating the ECM during normal brain homeostasis,and such processes may,in turn,become dysfunctional in disease.As it relates to synapses,microglia are reported to modify the perisynaptic matrix,which is the diffuse matrix that surrounds dendritic and axonal terminals,as well as perineuronal nets(PNNs),specialized reticular formations of compact ECM that enwrap neuronal subsets and stabilize proximal synapses.The interconnected relationship between synapses and the ECM in which they are embedded suggests that alterations in one structure necessarily affect the dynamics of the other,and microglia may need to sculpt the matrix to modify the synapses within.Here,we provide an overview of the microglial regulation of synapses,perisynaptic matrix,and PNNs,propose candidate mechanisms by which these structures may be modified,and present the implications of such modifications in normal brain homeostasis and in disease.
基金
This work was supported by the National Institutes of Health(NIH)under awards R01NS083801(NINDS),RF1AG056768(NIA),RF1AG065329(NIA),and U54 AG054349(NIA Model Organism Development and Evaluation for Late-onset Alzheimer’s Disease(MODEL-AD))to K.N.G.,F31NS108611(NINDS)to J.D.C.,and F31NS111882(NINDS)to M.A.A.We thank Rocio A.Barahona for providing whole-brain slidescan and 20×confocal images of microglia-depleted mouse brain sections immunohistochemically stained for perineuronal nets.The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
